The Miocene gas reservoirs
in the reemerging Veracruz Basin may provide a striking contrast to the
conventional exploration targets from the northern Gulf of Mexico. Attractive
drilling opportunities for oil and gas reserves in conventional deepwater
sandstone plays from the northern part of the basin have been successfully
identified from a combination of bright amplitudes and favorable structural
position. Seismic geometries commonly indicate stratal onlap onto salt
flanks or mud diapirs, giving rise to lateral pinch-out traps. These Miocene
through Pleistocene reservoirs are a mixture of sandy turbidite sheets/lobes
and sand-rich, variably amalgamated channel complexes as well as classic
leveed channel complexes, and most of the gas-bearing sandstones are low
impedance.

The Miocene deepwater
play of the Veracruz Basin has several important differences from its
northern cousin. Veracruz was fronted on the landward side by high-gradient
mountains, which shed sand and conglomeratic material into a tectonically
structured deep marine basin. These deposits are found today as high-impedance
reservoir bodies confined within erosional canyons or by shale-rich levees.
At least one gas field is the result of lateral and updip pinch-out of
conglomerates into shale. The lower and middle Miocene clastic feeder
systems transitioned into classic sand-rich fans that contain clear channel
elements that have trapped gas in meander bends draped over noses and
anticlines. As progradational clinoforms filled the basins remaining
accommodation space during late Miocene and lower Pliocene time, narrow
sinuous turbidite channels and associated small distributary complexes
formed. These channels contain stratigraphically trapped gas and represent
a new low-risk play that PEMEX is exploiting with the use of recently
acquired 3-D surveys. On balance, the turbidite systems from the Veracruz
have greater similarities to turbidite reservoirs currently being encountered
along the West Africa Atlantic margin (Angola, Nigeria) than those occurring
in the northern Gulf basin.